Compressor



J. BRAUN COMPRESSOR April 3, 1928. 1,664,733

Filed Dec. 7, 1922 2 Sheets-Sheet 1 April 3, 1928 2 Sheets-Sheei 2 Patented Ann 3, 1928.

"cairn arr aus'rus enema, on NUREMBERG, GERMANY.

' COMPRESSOR.

Application filed December 7, 1922, Serial No. 605,483, and in Germany March 8, 1922.-

This invention relates :to rotary compressors of the eccentric displacement type having an annular piston provided with a slide which engages in a swivel block rotatably mounted in the compressor casing, the PlStOll rolling over the inside wall of the casing.

The present invention has for its object provide an improved compressor of the type referred toin which the clearance space is reduced toa minimum, which is of simple and reliable construction and in which the compressed fluid sweeps over the smallest possible area of the swivel block on its way to the outlet port in the casing of the compressor.

In order that the invention may be clearly understood, 1 shall proceed to describe the same with reference to the two forms of construction shown by way of example in the accompanying drawings, wherein Figures 1 and 2 show one constructional form of the improved compressor in side elevation with one end cover removed and in a vertical axial section respectively.

Figures 3 and 4 show, respectively, in side elevation with one end cover removed and in vertical axial section a modified form of the compressor.

Referring to Figures 1 and 2, the casing of the compressor comprises a central portion 3 having a cylindrical bore 8 to which two covers 1 and 2 are fixed by means 0 connecting bolts 4 passed through holes in the covers and central portion. The two covers are provided with bearings" for the driving shaft 5 and the inner surfaces of said covers are well machined for the purpose of forming tight joints with the stationary middle art 3 and with the annular piston 7. The ore 8, which is concentric with the shaft 5 is well machined also and forms the piston chamber in which the an nular piston 7 is displaced by means of an eccentric 9 keyed on the shaft 5. The an' nular piston 7 is provided with an upwardly' extending slide 10, rigidly connected to it, said slide engaging in a guide slot formed in the swivel block 14: which is rotatably' mounted in the compressor casing, sothat the piston is prevented from turnin with the eccentric and can onl gyrate, t e periphery of the piston ro ling and sliding over the inner surface of the piston chamber 8, During the displacement of the piston by the eccentric the slide 10,osci1lates the swivel block 14 in the guide slot of which the slide reciprocat'es. The swivel block 1& is constructed so as to serve at the same time as an oscillating valve for cont-rolling the outflow of fluid from the piston chamber, and has a portion of its periphery adjacent the piston cut away so as to form on the suction side of the compressor, that is on the 'right hand side of the slide 10 in Figure 1, a'continuation of the wall of the cylindrical bore 8 when the piston is in the dead centre position. 011' the delivery side of the compressor, that'is to the left of the sli'de'lO in Figure 1, the periphery of the swivel block 14: adjacent the piston is cut away so as to form a flat, the edge 15 between this flat and the cylindrical part of the swivel block constituting a cut-off shoulder for the outlet port 16 which is in open communication with the transverse bore 17 which serves asv delivery conduit.

The relative positions of the cut-off shoulder of the oscillating valve 14 and of the outlet port 16 are selected in such a manner that the port is uncovered at the end of half the stroke of the piston and closed at the dead centre. The economical pressure limit would thus be fixed at approximately 2 to 3 atmospheres. In order to produce still higher pressures in an economical manner a curved spring 18 is inserted in the transverse bore 17 to cover the port 16 and f to act as check-valve. The spring 18 is fixed by inserting an ofiset portion 18 in a roove 17 in the wall of the bore secured.

The fluid is admitted to the compressor through an inlet port 6 in the part 3 which is covered by the side of the piston when the latter is in the 'dead centre position.

The operation of the compressor is as fol-' 17 inwhic h a is lows: In the dead centre position shown in Figure 1, both the inlet and outlet ports are covered. As the eccentric 9 is turned in the clockwise direct on the inlet port 6 is un-.

covered and remains uncovered until the iston again approaches the position shown 1n Figural. The outlet port 16, however, remains covered until the piston has travelled over half the circumference of the cylindricalbore 8 when the swivel block 14 uncovers the outlet port 16 and the compressed fluid is then foroed'into the delivery conduit 17 ,-the spring valve 18 yielding under the pressure of the fluid bein discharged from the piston chamber. T e outlet port is again covered as the piston reaches its dead centre position when the cycle commences afresh.

The lubrication of the compressor is effected by means of an oil circulating system. The oil flows into one bearing of the shaft 5 through the pipe 19 in which a throttling element 20 is arranged and the oil is conducted through the axial bore 21 of the shaft 5 to the several lubricating points. Through the radial bores 21 and 21 the oil flows to the bearings of the shaft and through the radial bore 21 it flows into the radial bore 22 of the eccentric. With the radial bore 22 of the eccentric intersects an axial bore 23 designed to conduct the oil to the lateral sliding faces of the eccentric, the

circumference of the same being lubricated from the bore 22.

The lubrication of the outer cylindrical surface of the annular piston 7 is effected through the bore 24 of the piston which terminates in the working space upon the suction side of the Pump at a distance from the slide 10 which is approximately equal to the radius of the swivel block 14. By suitably arranging the direction of the bore 22 it is ensured that this bore 22 registers with the bore 24 when the piston stands at the dead centre position. mined quantity of oil, adapted to be regulated by a throttle valve, can flow into the working space of the pump Whilst the piston is passing through the dead centre. This quantity of oil is pushed during the revolving ofthe piston in front of the contact line between the circumference of the piston and casing so as to form a gastight oil cushion but it flows partly also behind this contact line. This contact line is therefore permanently surrounded by a quantity of oil the surface tension of which, assisted by the capillary action, is greater than the gas pressure which normally exists in the compressor. The oil fills the out out parts of the swivel block 14 and the outlet slit whereby the clearance space is reduced and it flows'over to ther with the compressed gases through t e outlet port into the dos livery conduit 25 and from there into an oil separator .26. The inner circumference of the casing upon which the piston rolls is preferably roughened by etching in order to ensure a better adhesion of theoil.

The oil separator is constructed according towell known models and it serves at the same time as an oil reservoir for the reception of the lubricant which is continuously supplied to the compressor through the condult 19, the, compressed ases flowing to the point where they are to e used through the pipe 27.

The quantity of oil raised at each stroke of the compressor as oil cushion produces at the same time a cooling of the machine as the Through bore 24: a deter.

oil comes most intensively in contactjust with the points which are'most exposed to heat by the mutual sliding movement.

In the form of construction shown in Figs. 3 and 4 the lubricating is effected directly through a bore 28 in the centre portion 3 of the casing which terminates in the space 29 ofthe compressor into which enters ment into the delivery conduit and from this into the oil separator 26 from which it flows again through the conduit 30 into the bore 28 of the wall of the casing. The other parts of the compressor can be lubricated in a similar manner to that described in the form of construction shown in Fig. 1.

The compressor can evidently work also as a motor if the'check-valve 18 is removed, the cut off shoulder lfiregulat-ing the cut-off and expansion.

. By an arrangement so that the two parts of the swivel block may be axially displaced andby giving to the cut out partsofthe swivel block and to the cut-off shoulder 15 a helical shape the cut-off and expansioncan be regulated by hand or. automatically during the operatio a I claim 1. A rotary compressor, comprising in combination a casing, a driving shaft, an annular piston in said casing, a'n eccentri'con said driving shaft for displacing said piston, a swivelblock rotatably mounted in said casing-said swivel block. having a guide slot, an upwardly extending slide on said annular piston, said slide engaging in said guide slot so as to oscillate the swivel block during the cover on either side of said central portion,

an outlet port in said casing, a driving shaft,

an annular piston in said casing, an eccentric on said driving shaft for displacing said annular piston, a-swivel block rotatabl mounted in said casing, said swivel bloc having a'portio'n of its periphery cut away,

with the radial bore m said bearings,

to form on the suction sideof the compressor a continuation of the wall of the cylindrical bore, and on the delivery side so as to form a cut-off shoulder for the outlet port when the annular piston is in the dead centre position, a guide slot in said swivel block,

an upwardly extending slide on said annular piston, said slide engaging in said guide slot so as to oscillate the swivel block during the displacement of the piston and an inlet port in one of said covers capable of being covered by the side of the piston when the latter is in the dead centre position, as and for'the purposes set forth.

3. A rotary compressor as Set forth in claim 1, and having a transverse delivery ort in the casing in open communication with the outlet port and a curved spring fixed in said delivery port and adapted to isolate said delivery'port from said outlet port, as and for the purposes set forth.

4. A rotary compressor comprising in combination a casing, hearings in said casing, means for supplying lubricant to one of a driving shaft journalled in said bearings, said shaft having an axial hole adapted to receive lubricant from said bearing, an eccentric on said driving shaft,

an annular piston on said eccentric, radial bores in said shaft in open communication with said axial hole for conducting lubricant to the shaft bearing, a bore in said shaft in open communication with said axial hole, a radial bore in said eccentric for conducting lubricant from said axial hole to the periphery of the eccentric, axial bores in said eccentric in open communication with the axial hole in the driving shaft for conducting lubricant to the sides of said casing, a radial hole in said annular piston for con; ducting lubricant to the periphery of the piston, saidhole being adapted to register the eccentric when the piston is in the dead centre position, a swivel block rotatably mounted in said casing said swivel block having a guide slot, an upwardly extending slide on said annular piston, said s-iide engaging said ide slot so as to 0s llsl swivel block uring the displacement if the piston, an iniet port in surplus lubricant as and for the purposes set an annular piston on said eccentric, radla bores in said shaft in open communication with said axial hole for conducting lubricant to the shaft bearings, a bore in said shaft in open communication with said axial hole, a radial bore in said eccentric for conducting lubricant from said axial hole to the periphery of the eccentric, axial bores in saideccentric in open communication with the axial hole in the driving shaft for conducting lubricant to the sides of said casing, a swivel block rotatably mounted in said casing, said swivel block having a guide slot, an upwardly extending slide on said annular piston, said slide engaging in said guide slot so as to oscillate the swivel block during the displacement of the piston, an inlet port in the casing capable of being covered by the side of the piston when the latter is in the dead centre position, an outlet port in the casin capable of being obstructed by the swive block, a radial hole in said annular piston terminating at the periphery of the iston at a distance from the slide on the suction side thereof equal to the radius of the swivel block for conducting iubricant to the periphery of the piston, said hole being adapted to register with the radial bore in the eccentric when the piston is in the dead centre position, and means for conducting from the said outlet port to said reservoir, as and for the purposes set forth.

In testimony whereof I aifix mgiiiiature.

DIPL. 1N0. JUSTUS UN.

from the said outlet port to 

